Posted: Sun Mar 16, 2014 11:09 pm Post subject:
New to DIY and overwhelmedSubject description: Sorry if this is in the wrong section!

First off, I would like to say, before anything else, I do have a bit of experience with electrical circuitry. My father is an Electrical Contractor (Agricultural, Residential, Industrial; large scale, large voltage stuff mostly. 120AC or more) and I worked for him until fairly recently.

I know what AC and DC mean and are. I know what ground, going to ground, shorting to ground, whatever & ground, mean. I know positive and negative. I know hots and neutrals. I know a capacitor stores voltage, and thusly will increase output voltage by a set amount, and I know a resistor does the opposite; resisting voltage and dropping the output voltage. At least, I think that's how they work.

Now that that's out of the way...

Hi, I'm Rachel, I'm an EDM musician/DJ and at the moment I live in McKinney, Texas. I've been producing and DJing for going on three years now. I recently got interested in analogue and in general, hardware, synthesizers, sequencers, drum machines, the whole fun bunch.

I'm particularly interested in Grooveboxes. (Yamaha Rm1x, Korg Electribe EMX-1, ESX-1, Roland MC-303, 307, 505, 606, 707, 808, 909) The all-in-one ness is just... neat, for some reason. Yeah, I could click around for HOURS upon HOURS with my Komplete, and Ableton, and just... whatever. A thousand tools, maybe one or two of which I truly know well. I'm infatuated with the idea of working with what you have, and because I can't really shell out all the cash for a really nice Groovebox that actually works, I figure I could build one!

This got me into a bunch of stuff, my two main projects that I'm thinking about right now, are;

The Groovebox, of course. The plans so far go somewhat like this;

On the front of the box, from top to bottom;

Four oscillators on the tip-top, not sure exactly how they'll work technically, but I intend to put a pitch knob on it, and a wave select switch, (I'd like 2-3 waveforms per oscillator for the first four, but we'll see what I can manage) as well as a switch for outboard MIDI control, or control via the step sequencer. (More on that in a second)

Four more oscillators are below this. One is a kick drum oscillator. I'm thinking the NienOhNien (hexinverter.net is probably where these'll come from) which is a 909 clone, thinking another 909 clone from the same people for the snare, and their 'Mutant Hihats' for the open and closed hihats. However, I'm not able to find the page for these that I had found originally right now, and was dumb and only bookmarked the homepage, not the pages themselves. The issue with these is that they're designed for rack mounts, which means CV/Gate controls. I'd like to go with MIDI.

Below the 8 oscillators are the filter controls, and the volume faders. From right to left; Lowpass filter, cutoff and resonance knobs. Volume faders, then the highpass filter, cutoff and resonance knobs also. The filters all have 8 bypass buttons; so that you can run whatever oscillator through them individually, instead of them all being run through all the time without option for disabling it without just turning the resonance all the way down and the cutoff all the way up/down. There are 9 volume faders, one for each oscillator, and the master volume fader in the center.

And under all that, from right to left, (plans for this section are not drawn out yet) LFO1, FX Unit(s) (probably 3, maybe just 2) and LFO2. LFO's modulate the filters. Buttons on each for which filter's cutoff is being modulated, (and you can modulate one cutoff with both lfo's, if you wanna) as well as switch for the wave select on the LFO, (not sure I'll do that, might go with basic sines) and a knob for the amount of modulation, and the rate of modulation.

And last but not least, probably the most complex piece, (definitely) the step sequencer! 16 Steps, each step is a note, C, C#, D, D#, E, F, F#, G, G#, A, A#, B, C2, C#2, D2, D#2. However the notes do not effect the drum oscillators, which will all trigger at the same pitch, probably C. Tempo knob. Obligatory play/pause and record buttons. Record function also records the movement of all knobs that move at any point, during the recording. (Not any clue how to do this) 8 buttons to switch between which pattern you're editing, as well as 8 buttons to select which oscillators are playing through which pattern, (done by holding the button for the pattern, then pressing the button for the osc) 2 buttons marked + and -, - takes the keyboard down one octave, and + takes it up one octave. The keys also trigger the audio signal when simply pressed, while out of record mode, allowing you to play them like a keyboard. There are no automatic scales, those are input manually by the user. I'd like to incorporate a glide setting as well, and a knob to control just how much glide there is. However, I also want to incorporate a memory of some kind, so that you can save your stuff without having to export the MIDI via MIDI outs, and/or record via audio outs. Even then, it wouldn't be the same as just hitting "save" but I'll get to that in a bit.

And FINALLY, the back of the unit. 9 Audio outputs. 1 for each voice, and the master. MIDI ins and outs for each voice. And, of course, the power supply hookup.

That's just the first one, and I haven't even gotten to my questions yet.

The second one is a design for a portable synth version of the groovebox. It's two oscillators, (two of the same oscillators from the groovebox) roughly the same step sequencer. One midi in and out, both voices get played at once; though both oscs have volume knobs (or possibly mute buttons, haven't decided) the lowpass from the groovebox, bypass buttons, cutoff, resonance. LFO, rate and amount knob; always on, always effects the lowpass' cutoff. Turning the rate all the way down, turns it off. Two effects, not sure what ones yet. Two audio outs, one 1/4" and one 1/8" built in speakers, and runs on battery power. Sequencer can only play one pattern at once. Also has tempo knob, glide, glide amount, performance mode, play+pause/record buttons.

My questions!

So, if a schematic or plans or whatever call for a 10 Ohm resistor, no other specifications, just that. Can I use any resistor, or do I have to find, specifically, the exact resistor that they used? Hell, if I remember correctly, I could potentially use a 20 ohm resistor in place of a 10 ohm, because it covers what the 10 ohm can do. I think, anyway. And does this example apply also to capacitors, transistors, amps, whatever? Basically, can I take a schematic, and as long as I put all the capacitors where the capacitors go, and the resistors where the resistors go, and solder them together in the right order, can I use almost whatever parts?

Can I make the projects I want to make, without programming? I dislike coding, and I want to stay away from digital for these projects, but I also would like to use MIDI, because then it would integrate easier with my digital things, like my laptop and such.

Also, a pipedream, I'd really like to make these instruments and possibly others in the future, able to sync in tempo with one another.

Another pipedream is that I get good enough with circuitry that I can plan out and assemble my own pieces; filters and oscillators and all that. My own schematics, that are 100% original.

I'd also someday like to build a sampler drum machine. That's a long ways off though.

The way I intend to build these, is to find schematics online, grab the parts and a breadboard or two, and assemble them, tweaking them to my needs. For instance, the 'Mutant Hihats' I'd like to use, use CV/Gate inputs; I'd have to switch that to MIDI. Not to mention an accent input/function which I feel I won't be needing.

I suppose I could also just invest in a CV to MIDI converter, and use that when I want to record MIDI out or play MIDI in, and use CV on the units. That's my backup, however.

I'm also not sure what I want to do for FX units, I'd like a distortion of some kind, and I'm a big fan of chorus, but I also would like a delay. So many choices! Blagh.

I'm also curious, I've heard things, for example, there's a schematic running around this forum for a "4017 sequencer" does the 4017 mean something? Is that specific code or some such that means it's assembled in a certain way and is only compatible with other 4017 assembled parts?

I intend to build this by building the individual pieces, then stringing them together in the right order. Of course, it's not THAT simple, but we'll leave it there for now.

All the questions I've asked, Google was unable to answer.

Oh, and do you lot think any of these are neat ideas? I have a few others, ish.

First of all I have to say that in order to have a positive DIY experience I believe you should be doing it for the love of building something yourself, not just to have the end product cheaper than you can buy it for. In many cases you may not even save any money, economy of scale is a powerful factor in the electronics industry. And then there's the value of your time...

fox24 wrote:

So, if a schematic or plans or whatever call for a 10 Ohm resistor, no other specifications, just that. Can I use any resistor, or do I have to find, specifically, the exact resistor that they used? Hell, if I remember correctly, I could potentially use a 20 ohm resistor in place of a 10 ohm, because it covers what the 10 ohm can do. I think, anyway. And does this example apply also to capacitors, transistors, amps, whatever? Basically, can I take a schematic, and as long as I put all the capacitors where the capacitors go, and the resistors where the resistors go, and solder them together in the right order, can I use almost whatever parts?

Absolutely not. Some values aren't critical and can be fudged, others will have a negative impact on the performance of the circuit if they aren't exact. Sometimes you will substitute a different value to modify the behavior of a circuit.

There are usually several characteristics to consider besides the value including tolerance, power rating for resistors and voltage rating for capacitors, etc. There are also many different types of capacitors which will be used depending on the circuit (there's a sticky in this subforum on choosing capacitors). A good schematic will indicate most of these but a lot a schematics require a lot of "reading between the lines". There's a lot to learn here and sourcing components yourself rather than buying a kit can be very daunting especially for the beginner.

Quote:

Can I make the projects I want to make, without programming? I dislike coding, and I want to stay away from digital for these projects, but I also would like to use MIDI, because then it would integrate easier with my digital things, like my laptop and such.

MIDI and save/recall of sequences will probably require programming, the rest you can probably do without any programming.

Quote:

Also, a pipedream, I'd really like to make these instruments and possibly others in the future, able to sync in tempo with one another.

This actually isn't that difficult, sequencers usually have a clock input, just use one clock source.

Quote:

Another pipedream is that I get good enough with circuitry that I can plan out and assemble my own pieces; filters and oscillators and all that. My own schematics, that are 100% original.

Nobody does anything 100% original, you will always be borrowing from existing circuits and tweaking/arranging them to suit your needs. There are many books available that are references for common circuits used as building blocks. A lot of really smart people have done a lot of work already, no need to reinvent the wheel

Quote:

I'm also curious, I've heard things, for example, there's a schematic running around this forum for a "4017 sequencer" does the 4017 mean something?

The 4000 series is a family of standard logic IC's http://en.wikipedia.org/wiki/4000_series. The 4017 specifically is a decade counter, it counts from 1 to 10 with a single bit output for each step making it easy to implement a step sequencer.

Quote:

I intend to build this by building the individual pieces, then stringing them together in the right order. Of course, it's not THAT simple, but we'll leave it there for now.

Basically a modular synth.

Quote:

I know what AC and DC mean and are. I know what ground, going to ground, shorting to ground, whatever & ground, mean. I know positive and negative. I know hots and neutrals. I know a capacitor stores voltage, and thusly will increase output voltage by a set amount, and I know a resistor does the opposite; resisting voltage and dropping the output voltage. At least, I think that's how they work.

The opposite of a capacitor is an inductor. They both store energy (reactive components), capacitors resist changes in voltage, inductors resist changes in current. Resistors simply dissipate energy.

Hot and neutral aren't really used much outside of HV, +/- power supply rails and ground are what you're going to see more of in synth DIY.

Make Magazine (a publication by the publisher O'Reilly) has a series of books about learning electronics, and the series includes one by Ray Wilson (www.musicfromouterspace.com) about analog synths. I think you would be well served by looking into these:

The first one to get some grounding and a better understanding of how electronic circuits differ from electric power circuits, and the second one, obviously about synths .

As you seem to have already figured out, hexinverter.net is a great resource for DIY projects once you are comfortable soldering components. There are a number of others as well, including musicfromouterspace.com, synthcube.com, bridechamber.com, www.cgs.synth.net, as well as projects offered by many folks here on electro-music.com and over at muffwiggler.com (don't let the name put you off, it's based on some old guitar pedals). Fonik in particular is another person who regularly offers high quality DIY circuit boards.

Muff's tends to be a firehose--I can't remotely keep up with the volume there. But it's a great resource along side E-M here which has a more laid back pace.

Be warned: there's a black hole here and it will suck up time and money

Posted: Tue Apr 01, 2014 9:00 am Post subject:
Re: New to DIY and overwhelmedSubject description: Sorry if this is in the wrong section!

Hi Rachel!

fox24 wrote:

So, if a schematic or plans or whatever call for a 10 Ohm resistor, no other specifications, just that. Can I use any resistor, or do I have to find, specifically, the exact resistor that they used? Hell, if I remember correctly, I could potentially use a 20 ohm resistor in place of a 10 ohm, because it covers what the 10 ohm can do. I think, anyway. And does this example apply also to capacitors, transistors, amps, whatever? Basically, can I take a schematic, and as long as I put all the capacitors where the capacitors go, and the resistors where the resistors go, and solder them together in the right order, can I use almost whatever parts?

gdavis answered this, but I'll add that most really solid projects have at least rudimentary documentation on what parts to choose, which of them that are critical and not so critical, and so on. I'm still in my learning and preparing phase (partly because being unemployed means I can't afford extravagant hobbies ), and Thomas Henry's writings have been very educational for me. He's very good at explaining all these rather intricate things in synth circuits. I think it was he who got me to finally understand how oscillators and expo converters actually work. He has his own subforum here on e-m, and Scott Stites hosts many of his projects in his site.

Quote:

I'm also not sure what I want to do for FX units, I'd like a distortion of some kind, and I'm a big fan of chorus, but I also would like a delay. So many choices! Blagh.

I haven't seen many distortion modules around, for some reason. The Oakley Overdrive is one of them, and it does sound quite fantastic. Delay can be tricky, depending on whether you're hellbent on having an analog one or not. On the digital side it's easier, and there are many projects built around the PT2399 delay chip.
I guess it's not the easiest way, but the late Jürgen Haible posted many schematics of phasers, choruses, you name it, on his site here.

So, I've been digging around, particularly around the Schematics Vault thread here on electro-music, trying to find some designs that'd work well for me, or that I'd be interested in using, or what-have-you. I also have been trying to learn, though, symbols and ohms law and watt's law, and various abbreviations; bunches of stuff.

I've decided the portable synth version will be a better place to start, then I can expand it later into the Groovebox.

I have a couple more questions, now.

Firstly, sequencers. I want a sequencer that is just enough for what I wanna do. Frankly, I could care less about MIDI; I can use a CV/Gate to MIDI converter externally if I need to. Play/pause, with a CV in for tempo, (I intend to use a simple sine generator as the clock, with an in and out for that as well, so it can be bypassed to sync to other things, and have other things sync to it. Anyway, my issue is, all the schematics I'm finding, have the sequencer turning out like this;

Now, I'm looking more for, just, a single row of pushbuttons. Maybe two, one button selects the step, one selects the note/CV, but still nice, compact, pushbuttons; not a gigantic confusing array of knobs. I'm not building euroracks.

Now, also, say I wanted to add a mute button to a VCO schematic. I would just interrupt the output, right, with a switch? But where would that voltage go, if it was still receiving CV/Gate signals; would I wire it to ground? Or would it be safe to just leave it empty, interrupt the circuit and make the voltage go pretty much nowhere? Probably not, right?

Speaking of wiring to ground, where does the ground go on a battery powered device? Does it go to neutral or 0v or is there a way to feed it back into the battery to save the electricity?

Also, I realize this is probably pretty stupid, and I know it'll more than likely be a "no" but I'm curious as to whether I can, say, power a circuit made for running at +/-12v DC and run it off of a 9v battery? Or could I use two and run it off of 18v? I'm afraid I'd blow it at too much voltage, but how will not enough voltage effect it? Would it just be a volume drop? Or quality and performance drop, too? Also, if I can't power a circuit at, say, the aforementioned +/-12v DC, can I change the voltage that goes into it without changing the parts in the actually circuit? A series of resistors or whatever?

Also, for THRU controls, (thinking of having a THRU input to run external things through the filter and distortion units of the synth, with the regular output being the output) I just throw a switch in between the OSC's outputs and the filter's input, and route the input into it via the switch, with the switch flipped opposite no voltage would get through the THRU input and the oscs would connect. That's how that works, yeah? Provided I don't need any capacitors or anything to regulate the incoming voltage?

Also, if I just assembled a VCO circuit from a schematic, would I need to tune it? and I'd like to have the pitch knobs of the oscillator have several fixed positions, up and down for a few octaves, how do I tune that? with an adjustable resistor set-and-leave probably, but how would I measure the Hertz to make sure its in tune? and how would I tune the sequencer's notes? Can I measure Hertz with a volt meter or should I like, get a guitar tuner or something that can tell me the Hertz so I can tune the circuit? Would I even have to?

The plans for the portable synth look like this;

I forgot switches for wave select on the VCO, and the THRU stuffs, but it's more or less the same idea I have in my head. I wanna call it, "Bleep; The Little Blue Bass Box" teehee :3

I have circuit schematics for everything, I think. I have a 16 step sequencer, a lowpass filter, several VCO's, overdrive (where the "Drive" knob is) VCA, and a couple ringmods (the spot where it says "was thinking ringmod here?") I even have a LFO which I was planning on using as the clock. As well as a glide circuit I'm not 100% sure I know how works, (I think the input from the VCO's comes in and then out through the glide) I just need a power supply,

Speaking of LFO's, how does one wire that? Say, I want the LFO to control the lowpass filter's cutoff, but that of course has a knob, that I'd like to be able to adjust at the same time, so I can't just put a switch in for LFO control; they'd need to work together.

Also, the circle thing with the lines on the far right is the onboard mono speaker, (the whole thing is mono) how would I wire that up? Provided it's not like, 120v or AC or anything, Would I just hook it to the output, with a switch to make the output go back and forth between the speaker and the output(s) (Might have two outputs, one on 1/4" and one on 1/8")

And good news, I have a second interview here soon, looks like I'll get the position I applied for, which means I can start working and getting paychecks to actually start this, (of course payin' bills first, heh) which is super duper exciting!!

I'm curious though, where would I go to get parts? I know Amazon has some, but they're so expensive with everything these days...

So, I've been digging around, particularly around the Schematics Vault thread here on electro-music, trying to find some designs that'd work well for me, or that I'd be interested in using, or what-have-you. I also have been trying to learn, though, symbols and ohms law and watt's law, and various abbreviations; bunches of stuff.

I've decided the portable synth version will be a better place to start, then I can expand it later into the Groovebox.

I have a couple more questions, now.

Firstly, sequencers. I want a sequencer that is just enough for what I wanna do. Frankly, I could care less about MIDI; I can use a CV/Gate to MIDI converter externally if I need to. Play/pause, with a CV in for tempo, (I intend to use a simple sine generator as the clock, with an in and out for that as well, so it can be bypassed to sync to other things, and have other things sync to it. Anyway, my issue is, all the schematics I'm finding, have the sequencer turning out like this;

Now, I'm looking more for, just, a single row of pushbuttons. Maybe two, one button selects the step, one selects the note/CV, but still nice, compact, pushbuttons; not a gigantic confusing array of knobs. I'm not building euroracks.

Something like this?

Most folks building these use toggles rather than push buttons, because it can be complicated to get pushbuttons to show their state (unless they're big things with a clear "up" and "down" position).

Not entirely clear what you mean about buttons selecting the note though, that's always going to be a knob or a slider unless you've got an embedded microcontroller...

fox24 wrote:

Now, also, say I wanted to add a mute button to a VCO schematic. I would just interrupt the output, right, with a switch? But where would that voltage go, if it was still receiving CV/Gate signals; would I wire it to ground? Or would it be safe to just leave it empty, interrupt the circuit and make the voltage go pretty much nowhere? Probably not, right?

Speaking of wiring to ground, where does the ground go on a battery powered device? Does it go to neutral or 0v or is there a way to feed it back into the battery to save the electricity?

If there's an open circuit, no electrons flow, and nothing goes out of the battery. Just like a battery with nothing connected to it. Totally safe to cut the circuit as a mute, though it might be better to ground the other side, or else whatever was amplifying that will be picking up potential noise.

So.... kinda like this:

oscillator -> switch -> output to next stage

when the switch is flipped instead of making the connection between the oscillator and the output, you connect the output to ground. On a SPDT switch you'd have output on the center, oscillator on one side and ground on the other. Does that make sense?

fox24 wrote:

Also, I realize this is probably pretty stupid, and I know it'll more than likely be a "no" but I'm curious as to whether I can, say, power a circuit made for running at +/-12v DC and run it off of a 9v battery? Or could I use two and run it off of 18v? I'm afraid I'd blow it at too much voltage, but how will not enough voltage effect it? Would it just be a volume drop? Or quality and performance drop, too? Also, if I can't power a circuit at, say, the aforementioned +/-12v DC, can I change the voltage that goes into it without changing the parts in the actually circuit? A series of resistors or whatever?

It mostly depends on what the circuit does. Some circuits are going to require +/- 12V, others will run fine on +/- 9V (two batteries, but connected so that one battery's plus connects to the other battery's minus and that point is used as ground for the circuit. Running a +/- 12V circuit on 18V is going to fail for two reasons--not only too much voltage for the + rail, but zero voltage for the - rail....

fox24 wrote:

Also, if I just assembled a VCO circuit from a schematic, would I need to tune it?

Absolutely!

I'm skipping a bunch of other stuff right now, I'm sure someone may respond though. It's mostly a matter of time for me .

fox24 wrote:

I'm curious though, where would I go to get parts? I know Amazon has some, but they're so expensive with everything these days...

Thank you all so much for your help, I really appreciate it! <3

Parts, especially pots and switches and jacks, are going to be expensive. Amazon probably isn't your best bet though. Some places I regularly buy things from that are less expensive, are Tayda Electronics and Unicorn Electronics, Smallbear, Mammoth. You can also get nearly everything from the big electronic parts distributors, Mouser, Jameco, Digi-Key, Newark, and I'm probably forgetting a couple. While the big boys are more expensive in small amounts, for some things (switches for example) you definitely get what you pay for.

me thinks it would be a good idea to start with some modules from the Lunetta topic...

well, it's almost "only" cmos circuits but they are easy to build and unexpensive (except the knobs and pots as stated before)

why not going to build it in a modular vein so you can always add several circuits to it...

i've managed to get 5 of these old Aluminium Brief cases in which i fit a wooden ground to Mount my modules on it... can bee seen on the case which is already filled...
..and it's portable as you can see... just depends on wherein you mount your stuff ...if it would be a car it would become a wheeled modular

i'm now starting to fill the 2nd case which will be merely cmos stuffed inside...
first i got 2 4046 vco's which can play via sequencer, cv out from any keyboard or twiggle manually with an pot... when providing an external 5V output to the case i can later plug in an ribbon controller to play with it or something with optoresistors... theremin style
the parts count for these where very low and it's very easy to build.. see pic below... i've slightly modified slackers design of a simple 4046 vco and stole the sync idea from Thomas Henry's 4046 VCO's schematic which i figured out the way i did is what most people here call the pitch tracking effect...

just add some lfo's, filters and logic gates xor and or, some dividers, vca's a small sequencer and you'll get an nice working sound machine...

below you'll also hear a Sound sample of one of those 4046 vco's...
first i played it with the cv out from my korg ms20... then noodling on the keys and using Manual control pot from 0.35 on... later some glide added... and at least the pitch tracking/sync function at the end switched on and off...

Firstly, sequencers. I want a sequencer that is just enough for what I wanna do. Frankly, I could care less about MIDI; I can use a CV/Gate to MIDI converter externally if I need to. Play/pause, with a CV in for tempo, (I intend to use a simple sine generator as the clock, with an in and out for that as well, so it can be bypassed to sync to other things, and have other things sync to it)

A baby 10 would be my guess for a simple sequencer. You can select the number of steps (2..10), add reset, start/stop buttons and could control
those externally aswell. A sinewave isn't useful as a clock, you'll need a square-/pulsewave. Unless you add a comparator which will turn the sine
into a square/pulse. You could also make a simple VCLFO using a CD4046 to clock the sequencer which gives you voltage controlled tempo.

Quote:

Now, I'm looking more for, just, a single row of pushbuttons. Maybe two, one button selects the step, one selects the note/CV, but still nice, compact, pushbuttons; not a gigantic confusing array of knobs. I'm not building euroracks.

as elmegil mentioned that's gonna need a microcontroller. well you could probably do it without but that would be a very large circuit.
Maybe you could use an arduino I know bubzy is doing something like that.

Quote:

]Speaking of wiring to ground, where does the ground go on a battery powered device? Does it go to neutral or 0v or is there a way to feed it back into the battery to save the electricity?

with a single powered device (one battery): GND = - or it could use a fake GND setup, where GND = 1/2 supply voltage (4.5V)
with a dual supply device (2 batteries): GND = 0V
(as elmegil said: connected so that one battery's plus connects to the other battery's minus and that point is used as ground for the circuit)

Quote:

Also, I realize this is probably pretty stupid, and I know it'll more than likely be a "no" but I'm curious as to whether I can, say, power a circuit made for running at +/-12v DC and run it off of a 9v battery? Or could I use two and run it off of 18v? I'm afraid I'd blow it at too much voltage, but how will not enough voltage effect it? Would it just be a volume drop? Or quality and performance drop, too? Also, if I can't power a circuit at, say, the aforementioned +/-12v DC, can I change the voltage that goes into it without changing the parts in the actually circuit? A series of resistors or whatever?

depends on the circuit,. some circuits designed for +/-15V run fine on +/-12V or +/-9V (2 batteries) without any adjustments. But you often have to make some adjustments which vary for each circuit.

Quote:

Also, for THRU controls, (thinking of having a THRU input to run external things through the filter and distortion units of the synth, with the regular output being the output) I just throw a switch in between the OSC's outputs and the filter's input, and route the input into it via the switch, with the switch flipped opposite no voltage would get through the THRU input and the oscs would connect. That's how that works, yeah? Provided I don't need any capacitors or anything to regulate the incoming voltage?

Yes that should work, you could use a jack with a switch contact so it disconnects the oscillators when you plug something else in.

Quote:

Also, if I just assembled a VCO circuit from a schematic, would I need to tune it? and I'd like to have the pitch knobs of the oscillator have several fixed positions, up and down for a few octaves, how do I tune that? with an adjustable resistor set-and-leave probably

With a V/oct VCO you can use a (rotary) switch and some resistors to select between octaves, or notes. You could actually add that to a sequencer .

Quote:

but how would I measure the Hertz to make sure its in tune? and how would I tune the sequencer's notes? Can I measure Hertz with a volt meter or should I like, get a guitar tuner or something that can tell me the Hertz so I can tune the circuit? Would I even have to?

you'll need to tune the VCO, for which you could use something like this and when using a sequencer you'll either tune by ear or again measure each step (or use switches).

Quote:

I have circuit schematics for everything, I think. I have a 16 step sequencer, a lowpass filter, several VCO's, overdrive (where the "Drive" knob is) VCA, and a couple ringmods (the spot where it says "was thinking ringmod here?") I even have a LFO which I was planning on using as the clock. As well as a glide circuit I'm not 100% sure I know how works, (I think the input from the VCO's comes in and then out through the glide) I just need a power supply

That would be the first thing to start with,. and you'll have to decide what voltages to use and what levels for CV, gates, trigger etc.

Quote:

Speaking of LFO's, how does one wire that? Say, I want the LFO to control the lowpass filter's cutoff, but that of course has a knob, that I'd like to be able to adjust at the same time, so I can't just put a switch in for LFO control; they'd need to work together.

For external control (LFO) you'll use a CV input, and you can add an attanuator to control the amount of modulation. You could use a mixer to use more then one CV source and you'll often see that in the case of a VCF the main frequency control and CV input are just mixed together. Where the main control will be an adjustable DC voltage.

Quote:

Also, the circle thing with the lines on the far right is the onboard mono speaker, (the whole thing is mono) how would I wire that up? Provided it's not like, 120v or AC or anything, Would I just hook it to the output, with a switch to make the output go back and forth between the speaker and the output(s) (Might have two outputs, one on 1/4" and one on 1/8")

you'll need a small amplifier to drive the speaker, and you can have both the speaker on and output at the same time. But you could use a switch or a jack with a switch contact so when you plug a cable in the speaker gets muted. (you could also use this for a headphone output)._________________"My perf, it's full of holes!"http://phobos.000space.com/http://www.acidtrash.com/Stickney Synthyards

welcome from a fellow newbie(ish) to SDIY. It is easy to feel overwhelmed but if you start simple at first, learn from your mistakes and ask questions youll be OK. Also if at first you blow things up dont worry event the best folks do that. Its all part of learning and building electronic circuits

You might want to look for the drum schematics for the monotribe. Korg will give these out by request so you can probably find them all over. This would give you a few drum voices that would run off 9v. It won't get you everything you want but would get you some useable drum sounds with a really low part count. Even if your not a modular person (which is mind boggling to me!) I'd pick a function to start like an oscillator or a bass drum. Glad to see someone so ambitious. let us know how it goes.

I'm still jobless and as such am still broke and have not been able to successfully begin much more than tinkering with a borrowed soldering iron, some solder I literally found while out on a walk, and some junk parts from the inside of a TV, (I think?) Plus its hotter than HELL here, so yeah, the garage is uninhabitable for any length of time. Even just having a smoke at night in there almost induces a stroke, lol.

Anyway, I have questions, again, after a fair bit of study.

Firstly, like, @elmegil, do you have the schematics for that sequencer you posted? It looks dandy.

I've made it a habit of collecting various schematics and just storing them all in a folder for future use. I never know which ones will be useful so I've been stashing them all. xD

Anyway, I have some questions about a little board I have from the guts of that TV, hypothetically, if I hook a 9v battery's plus to it, and a little speaker's negative side to the negative side from the battery, and connect the speaker somewhere, it should drone out a solid tone, yeah? It doesn't. It just clicks at me as soon as it connects. So I figured I'd boost or lower the capacitance or resistance to try and get the frequencies either up or down to a point that actually comes out of the speaker, 'cause I figured that was the problem, the click was the power connecting, and the buzz was too high to hear or wasn't coming out of the little speaker I have. Well, adding some fat resistance made it crackle and more white-noisey, but still only on connect or if I rub the leads together. No good if I want to solder it and leave it. What am I doing wrong?

Here's the board. The two black wires that are on the same end of the board are where I've been connecting power and the speaker, and also trying on random spots around the board. The one all by itself on one end doesn't connect to anything, anymore. The component it fed is broken and there's no connection between it and the others.

There's also a small knob type thing, it has one large wire off the top, with one little solder connection underneath, I removed it from another circuit board, and I can't really figure out how to connect it to anything else. I'm not sure it's a resistor... I'll find a picture of it.

Also, I've been thinking, I'd like to start off with a simple drum synth, just four drum sounds, monophonic, the 9v 8 step sequencer from Casper Electronics, no big deal, and I want to, of course, make it portable with a small vca and a speaker. I don't have any money though, so I've been considering starting a kickstarter, because it'll be rather simple, and if I can make a decent one for a decent cost, I might be able to pay some bills, which'd be awesome, and also have money to keep working on other projects. Would that be a good idea? I dunno if anyone would go for it. The first bit of money would be for parts and tools, and prototyping, and the rest would go toward paying bills, probably, and possibly making more so everybody can have a nice little drum box. Small step down from Volca Beats, step up from nothing.

Here's a picture of the concept design for the face of the drum synth.

Note sure what sound I'll do for the 4th voice, was thinking possibly a simple 555 square wave, but I'll probably just do another small drum voice derived from tinkering with one of the other schematics I have laying around. And the spot with the blue circle... I just thought it was weird to have a random spot that was empty, why not fill it? I figured I could experiment with the sequencer, possibly rig up a momentary contact button to be sort of a "Break button" where it'd send random triggers from all four sequencer paths out to the four voices, effectively causing a drum break to sound, before returning to the original programmed sequence upon release.

Also, just for shiggles, I pretty much finished the concept for the portable 2 osc bass synth in the previous posts here,

Circuits have been more or less discovered for this, the power supply and the actual innards themselves really depend on what power supply I decide I can use. One the black name plate, from top to bottom and left to right, the top two grey holes are CV/Gate In the bottom two are CV/Gate Out, the one in the center of the name is the THRU for the filter & Effects, the large grey circle on the right is the 1/4" output, the smaller one on the right is the 1/8" output.

Yay. Again, no prototyping has been done, 'cause I can't afford anything outside of gas/food.

Also where would I find audio jacks with the switch contacts a couple of you guys' mentioned? I've checked several of the retailers mentioned, as well as some others, and come up short.

The assumption that it should make sound is a bit dangerous. For this to happen the output you were hooking up to would have to have enough out put to drive a speaker and to be oscillating at a frequency within the range of the speaker.

The only thing I can see for sure is that it's damaged. T801 looks like it got a chunk taken out of it. But it looks to me like that might be doing something with the horizontal and vertical sync pluses. I'm guessing that H_P and V_P are horizontal and vertical pulse for the picture timing. I'd take a look at the data sheet for those chips might give you some clues. I'd be surprised if that board did anything as is. It looks like its expecting an input from something else to me.

If your old school like me the 1/4" jacks with switches I use are the Switchcraft 112AX don't use 1/8" so can't comment on that. Good luck

I made some modifications, and only did 8 steps, but that's the core of it.

Thank you!!

forshee wrote:

Hi again Rachel,

What makes you think that board is for audio?

It's electronics... Electricity moves from source, like a battery, through the paths determined by wire or PCB or whatever, it moves electrons, the electrons then make the cone of the speaker move and displace air molecules, yada yada.

In theory, it doesn't matter what the board was designed for, if I run electricity through it, and out to an audio source, it'll make a noise. Maybe not a musical noise or a waveform that makes sense like a sine or square or saw, but it'll make a noise none-the-less.

... Right? Why wouldn't it? All an osc is, in its simplest form, is just a series of circuitry that generates a waveform. Why wouldn't this board do that?

elmegil wrote:

The assumption that it should make sound is a bit dangerous. For this to happen the output you were hooking up to would have to have enough out put to drive a speaker and to be oscillating at a frequency within the range of the speaker.

The only thing I can see for sure is that it's damaged. T801 looks like it got a chunk taken out of it. But it looks to me like that might be doing something with the horizontal and vertical sync pluses. I'm guessing that H_P and V_P are horizontal and vertical pulse for the picture timing. I'd take a look at the data sheet for those chips might give you some clues. I'd be surprised if that board did anything as is. It looks like its expecting an input from something else to me.

T801 is definitely broken, I don't know how it did, I didn't remove these parts from whatever they came out of, (likely a TV, as I said)

So far, out of the huge, massive, (like, the biggest one is almost a square foot) busted up PCB's, there are more than a dozen, almost two dozen, IC's.

I haven't been able to find a datasheet for one. Not even one. I google all the numbers on them, together, separate, with the numbers, with the letters, with both of course, and just... nothing.

Plus, I've had some real trouble removing IC's, and, honestly, lots and lots of trouble removing components that have more than 3 leads... =/ I don't have a solder sucker thingy, so the solder just re-solidifies as soon as I move away from it.

elmegil wrote:

If your old school like me the 1/4" jacks with switches I use are the Switchcraft 112AX don't use 1/8" so can't comment on that. Good luck

Well DC IE a steady state will do nothing or harm the speaker. For example if you just hook the battery to the speaker you'll hear a pop (the voltage quickly moving to 9V) and then nothing. But the 9V is still moving through the speaker causing it to heat up and depending on the conditions burn up.

A little amplifier (like the Ruby amp) and an audio probe (cap on a wire) would be really good starter projects and necessary tools in the long run for debugging. This blocks the DC from getting to the speaker and amplifies small signals so that you can hear them.

If you open up a random device most of the point you probe at (even with the setup above) wont make noise for a number of reasons. They might be a power signal witch would just give you that quick pop. They might be sub sonic (like the signal that turns the screen on and off). Or supersonic like the pixel clock for 720p is 74.25MHz well outside the hearing of any animal! Or the signal may be too weak to drive the speaker. It dose take some power to get that cone moving!

Reading codes off chips is a bit of an art. Much of what printed wont mean anything to you. I can't see much but JRC is New Japan Radio Corporation. My guess is that the part number is the one under it. Generally, you'll have more luck by typing it into a parts supplier (digikey or mouser are good bets) then a google search. But that may now work if it's been discontinued for a long time. If you list whats writen on it I can probably help you track it down.

I'm with you on desoldering things! It's still a pain even with nice tools and it might now work when you get it out! The cheep way is to heat the joint the quickly whack the board on the table. That can work well enough sometimes.

I hope that answers some of your questions. If not let me know and I'll give it another shot. Some times us technical types make really lousy teachers!

I looked at them earlier today, the IC's on this board are 2x 2903D-JRC-1024J and 1x 2904D-JRC-2056G. At least I think its a G, my glasses need replaced, though, heh.

Also, I tinkered a bit today, the two black leads from the one end of the board? They fell off completely. Just snapped off. I tried to re solder some longer ones on, and my soldering iron wouldn't get hot enough to do anything other than make some shiny balls of solder >.> Damn 25 watt. Good thing it isn't mine.

Also, this seems like a stupid question, why does a potentiometer have three leads?

I mean, reasoning tells me that lead 1 connects to where lead 2 is connected when the knob is all the way to one side, and lead 3 connects to where lead 2 is connected when the knob is all the way to the other side, and in the middle, the signal gets split, and yada yada, right? That's how they work, right? Same with switches that have three leads? Yeah?

I've been busy with other things lately, have not had the chance to get the codes off of the other IC's on the other boards. :3

I'm not 100% sure I'll be able to make the pocket sized drum synth for the price I'd like. The plans I posted for it would put it at, with just the parts for the visible pieces, (The knobs, switches, pots, speaker, other switch, input(s) ouputs, and LED's) would be more than $50. Kind of a bummer but I redesigned it and now, it should be about $35, for the visible stuff, which are also the most expensive parts, incidentally. Besides the OSC IC's I had to remove 2 drum voices and 2 channels of the sequencer, however. Though, it did also cut down on the size. Making it more pocket friendly. :3

Also, this seems like a stupid question, why does a potentiometer have three leads?

I mean, reasoning tells me that lead 1 connects to where lead 2 is connected when the knob is all the way to one side, and lead 3 connects to where lead 2 is connected when the knob is all the way to the other side, and in the middle, the signal gets split, and yada yada, right? That's how they work, right? Same with switches that have three leads? Yeah?

Yes, potentiometers are often used as voltage dividers.
You can for example use this to control a (control) voltage by wiring say lead 1 to +12V, lead 3 to ground - on the wiper lead 2 you will get a voltage between 0 and 12V.
You can use this to dampen a signal (going into or out of your circuit for example), you wire the full signal on lead 1, ground on lead 3 - now you have a variable amplitude signal on lead 2.

You can also wire them as "variable resistors" (short the wiper, lead 2, to either end).

Yep looks like those are comparators. Here's a link to the JRC parts but lots of people make the same part. The 2903 is the full part number the rest is manufacturer, lot code, package information, probably temperature rating all sorts of stuff that doesn't matter here.

It's electronics... Electricity moves from source, like a battery, through the paths determined by wire or PCB or whatever, it moves electrons, the electrons then make the cone of the speaker move and displace air molecules, yada yada.

In theory, it doesn't matter what the board was designed for, if I run electricity through it, and out to an audio source, it'll make a noise. Maybe not a musical noise or a waveform that makes sense like a sine or square or saw, but it'll make a noise none-the-less.

It's electronics... Electricity moves from source, like a battery, through the paths determined by wire or PCB or whatever, it moves electrons, the electrons then make the cone of the speaker move and displace air molecules, yada yada.

In theory, it doesn't matter what the board was designed for, if I run electricity through it, and out to an audio source, it'll make a noise. Maybe not a musical noise or a waveform that makes sense like a sine or square or saw, but it'll make a noise none-the-less.

thats true fox! if you use a big amp with this yada yada this one can open a wormhole... so be carefull!

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot vote in polls in this forumYou cannot attach files in this forumYou can download files in this forum

Please support our site. If you click through and buy from our affiliate partners, we earn a small commission.